and are referred to as radiation [1]}, [2]}, [3]} and backreaction BC [4]}, [5]}, [6]}, [7]}, respectively. The radiation BC (Eq. (REF )) describes an irreversibly, partially reactive boundary. The limiting cases of a completely reactive (absorbing) BC [8]} corresponds to \(\kappa _{a}\rightarrow \infty \) , while a non-reactive pair is described by \(\kappa _{a}=0\)  (reflective boundary). The backreaction BC (Eq. ()) takes into account dissociations also. Clearly, in the limit of a vanishing dissociation constant \(\kappa _{d}\rightarrow 0\) , the backreaction BC reduces to the radiation BC. The survival probability \(S_{\text{rev}}(t\vert r_{0})\)  that appears in the backreaction BC is defined by
\(S_{\text{rev}}(t\vert r_{0}) = 4\pi \int ^{\infty }_{a}p_{\text{rev}}(r,t\vert r_{0})r^{2}dr.\) 
